Ikarus C42 FB100, G-CDNR No & Type of Engines
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AAIB Bulletin: 5/2017 G-CDNR EW/C2016/03/01 ACCIDENT Aircraft Type and Registration: Ikarus C42 FB100, G-CDNR No & Type of Engines: 1 Rotax 912 ULS piston engine Year of Manufacture: 2005 (Serial no: 0507-6696) Date & Time (UTC): 20 March 2016 at 1600 hrs Location: Stoke Airfield, near Burrows Lane, Middle Stoke, Kent Type of Flight: Private Persons on Board: Crew - 1 Passengers - None Injuries: Crew - 1 (Fatal) Passengers - N/A Nature of Damage: Aircraft destroyed Commander’s Licence: National Private Pilot’s Licence (Aeroplanes) Commander’s Age: 61 Commander’s Flying Experience: 117 hours (of which 17 were on type) Last 90 days - 2.5 hours Last 28 days - 1.5 hours Information Source: AAIB Field Investigation Synopsis The pilot, who was converting to three-axis microlights, was flying solo following three training flights that morning. The aircraft was seen to become airborne and then climb very steeply, achieving an extreme nose-up attitude. The left wing dropped and the aircraft descended, colliding with high tension power cables adjacent to the runway. It then struck the ground and an intense post-crash fire broke out. The pilot was fatally injured. History of the flight The pilot had qualified as a weight shift microlight pilot in August 2013 and decided to convert to three-axis microlights in 2015. His first solo flight in a three-axis aircraft was in the Ikarus on 12 February 2015, after 13.75 hours of training. He had made an appointment to take up three-axis flying again on 20 March 2016. The instructor arrived at the airfield at approximately 1000 hrs and checked the weather. The forecast was for a 1,400 ft cloud base with a light wind down Runway 06, which was suitable for training and solo flights. He moved the aircraft out of the hangar, carried out the daily inspection and then washed it. The pilot arrived at about 1130 hrs and discussed with the instructor the plan for the day, which was to make a number of 30-minute flights to continue his three-axis training. They © Crown copyright 2017 18 AAIB Bulletin: 5/2017 G-CDNR EW/C2016/03/01 conducted two training flights in the morning, covering takeoffs, climbing, emergencies in the circuit and use of flaps. As expected, after a year since his last three-axis flight, the pilot was a “little rusty” on the first couple of landings. Following a demonstration by the instructor and some further practice, the pilot improved measurably to a competent solo standard. Following a debrief in the cockpit, the instructor took the pilot into the training room and gave him a presentation on the use and effects of different flap settings. He also talked about the importance of aircraft attitude during a go-around. They carried out a third dual flight during which the instructor simulated an engine failure after takeoff, followed by a simulated engine failure downwind, from which the pilot landed. He flew competently on his second circuit and seemed calm and ready to go solo. The engine was shut down and the instructor briefed the pilot to fly out to the Isle of Sheppy, an area that he was familiar with, and practise some climbing and descending turns. The pilot seemed happy to be flying solo again and, after restarting the engine, taxied back to the threshold of Runway 06. The instructor observed the takeoff. He heard the pilot apply full power and saw the aircraft become airborne. It climbed very quickly and reached a very high nose-up attitude, which the instructor described as the aircraft “hanging on its prop”. The aircraft drifted left over the railway line that runs alongside the runway before dropping the left wing, descending and striking a set of high tension power cables. There was a bright flash and the aircraft fell to the ground. The instructor and club members ran to the accident site and attempted to extinguish the post-crash fire with handheld fire extinguishers. The pilot had sustained fatal injuries. Accident site The aircraft had come to rest in a field adjacent to the northern edge of the airfield, beneath power cables carried on pylons running in a southwest-northeast direction (Figure 1). The airstrip is slightly curved and is bordered by marshy ground to the south and a railway line to the north. A line of pylons runs north of and roughly parallel to the railway and carries 400kV electricity cables. Each pylon has three arms, with the power supply cables attached to the end of each arm. A separate phase is carried on each arm, with four cables in each phase. The aircraft had struck the southern array of cables (ie the ones on the airfield side of the pylons), causing an electrical discharge across two phases. © Crown copyright 2017 19 AAIB Bulletin: 5/2017 G-CDNR EW/C2016/03/01 Figure 1 View of accident site, looking along Runway 06 The aircraft had come to rest in an inverted attitude, with the nose pointing roughly parallel to the runway heading, ie 060°. The wreckage had burnt out, with the fire in the forward fuselage having been particularly intense. It was apparent that the right wing had separated close to the root as a result of striking the cable group mounted on the centre arm on the south side, approximately 100 ft above the ground. The right wing was found approximately 13 m from the main wreckage. The cables had not been severed, but had sustained damage in the form of broken cable strands (Figure 2). Photo: National Grid Figure 2 Damage to power cables © Crown copyright 2017 20 AAIB Bulletin: 5/2017 G-CDNR EW/C2016/03/01 The cable group below the damaged ones exhibited some slight scuffing, possibly as a result of a brushing contact with the underside of the left wing; this showed evidence of light scuff marks on the wing struts, with several holes resulting from severe electrical discharges that had caused localised vaporising of the aluminium alloy. Similar features were observed on the structural members of both wings and on flying control components, with some of the flying control tubes having melted. The positions of the discharge damage on the wing struts was consistent with the spacing of the cables within the group (Figure 3). Figure 3 Underside of right wing showing electrical discharge damage and possible cable contact positions The fabric covering of the left wing, which had remained attached to the fuselage, had burnt away, although there was little evidence of significant heat on the ground, leading to the conclusion that the fabric may have been ignited by the electrical discharge. The fuel tank, located behind the cockpit, had burst on impact and the burning fuel had consumed most of the forward fuselage. There was a shallow crater beneath the engine, but no other ground marks. The propeller blades had all broken at the approximately mid-span point, suggesting power at impact, although it was not possible to quantify this. The right wing leading edge spar had been broken just inboard of its mid-span point, as a result of contacting the cables. A foam fillet had been bonded to the front face of the tube, giving an aerodynamic shape to the leading edge. An indentation was apparent in the foam, close to the spar fracture, which was consistent with being made by one of the cables (Figure 4). As can be seen, the cable would have been approximately vertical relative to the wing leading edge, suggesting the aircraft was in a near vertical nose-down attitude at the time. © Crown copyright 2017 21 AAIB Bulletin: 5/2017 G-CDNR EW/C2016/03/01 Figure 4 Likely cable contact on the right wing leading edge spar It was concluded, from the available evidence, that the right wing had struck the middle set of cables on the south side of the pylons whilst the aircraft was in a steep, probably vertical, nose-down attitude. It is likely that this caused a yaw to the right, bringing the left wing into light contact with the lowest set of cables, resulting in the phase-to-phase discharge that in turn produced the bright flash and explosion reported by witnesses. Following an inspection of the site, the wreckage was recovered to the AAIB’s facility for a detailed examination. Aircraft information General The Ikarus C42 is a two-seat high-wing aircraft with a tricycle landing gear. It is manufactured in kit form or as a complete aircraft. Factory-built examples are dealt with by the British Microlight Aircraft Association (BMAA), and are approved as microlights. The Light Aircraft Association (LAA) deals with the kit versions, which can be either a microlight or Group A aircraft. G-CDNR was a factory-built aircraft and was classed as a microlight. The airframe primary structure is of bolted and riveted aluminium tube construction, the main structural member being a tubular boom that carries the empennage at the rear and the engine and nose landing gear at the front. The fuselage is given a conventional external shape by virtue of non-structural composite mouldings. The flying surfaces are covered with pre-stitched reinforced polyester envelopes. The engines approved for use in the Ikarus are the Rotax 912 UL (80 hp) and 912 ULS (100 hp). © Crown copyright 2017 22 AAIB Bulletin: 5/2017 G-CDNR EW/C2016/03/01 The flight controls are operated by a ‘side stick’ mounted on a console between the front seats. The top of the stick incorporates two buttons that respectively apply nose-up and nose-down elevator trim, the electric trim actuator being mounted within the left tailplane and operating a trim tab attached to the trailing edge.